1. Field
Example embodiments relate to a reflective extreme ultraviolet mask and a method of manufacturing the same. More particularly, example embodiments relate to a reflective ultraviolet mask having a reflective layer, and a method of manufacturing the reflective extreme ultraviolet mask.
2. Description of the Related Art
As a design rule of a semiconductor device reduces a wavelength of a light used in an exposing process also reduces. Thus, a minute pattern may not be formed using a light such as an I-line, a G-line, a KrF, an ArF, or the like. Therefore, an extreme ultraviolet (EUV) light having a short wavelength may be used in the exposing process.
However, because the light may have high energy, most of the EUV light may be absorbed in an absorbing layer of an EUV mask, so that the EUV light may not arrive on a semiconductor substrate. To overcome this drawback, a reflective EUV mask capable of using a reflected EUV may be used.
A conventional EUV mask may include a mask substrate, a reflective layer on the mask substrate and an absorbing layer pattern on the reflective layer. An edge region of the absorbing layer pattern may correspond to a non-patterned region that may not be used in an exposing process. An EUV light reflected from a portion of the reflective layer under the edge region of the absorbing layer pattern may interfere with an EUV light reflected from a portion of the reflective layer under a patterned region of the absorbing layer pattern. Therefore, it may be required to decrease a reflectivity of the portion of the reflective layer under the edge region of the absorbing layer pattern.
In order to decrease the reflectivity of the portion of the reflective layer, the edge region of the absorbing layer pattern and the portion of the reflective layer may be removed by a plasma etching process using a photoresist pattern. Because the portion of the reflective layer may be relatively thick, the portion of the reflective layer may be removed by the several plasma etching processes.
This may cause a long time for manufacturing the reflective EUV mask. Further, because a plurality of the photoresist patterns may be used in the plasma etching processes, byproducts generated from the photoresist patterns may act as critical defects of the reflective EUV mask.
Moreover, a width of the absorbing layer pattern may determine a width of a desired pattern. A width of a portion of the absorbing layer patterns may be different from that of other absorbing layer patterns, so that a portion of the reflective layer under the portion of the absorbing layer pattern may have a reflectivity higher than that of other reflective layers. When a pattern may be formed using this abnormal reflective EUV mask, the pattern may not have a desired shape.
Furthermore, the reflectivity of the reflective layer may not be locally controlled. Thus, the abnormal reflective EUV mask may be discarded. As a result, it may be required to manufacture a new reflective EUV mask.